*. To whom correspondence may be addressed. E-mail: jun.wang@nigpas.ac.cn or hpfeffer@sas.upenn.edu

Abstract

Plant communities of the geologic past can be reconstructed with high fidelity only if they were preserved in place in an instant in time. Here we report such a flora from an early Permian (ca. 298 Ma) ash-fall tuff in Inner Mongolia, a time interval and area where such information is filling a large gap of knowledge. About 1,000 m2 of forest growing on peat could be reconstructed based on the actual location of individual plants. Tree ferns formed a lower canopy and either Cordaites, a coniferophyte, or Sigillaria, a lycopsid, were present as taller trees. Noeggerathiales, an enigmatic and extinct spore-bearing plant group of small trees, is represented by three species that have been found as nearly complete specimens and are presented in reconstructions in their plant community. Landscape heterogenity is apparent, including one site where Noeggerathiales are dominant. This peat-forming flora is also taxonomically distinct from those growing on clastic soils in the same area and during the same time interval. This Permian flora demonstrates both similarities and differences to floras of the same age in Europe and North America and confirms the distinct character of the Cathaysian floral realm. Therefore, this flora will serve as a baseline for the study of other fossil floras in East Asia and the early Permian globally that will be needed for a better understanding of paleoclimate evolution through time.

Now if only someone would find one for the LATE Permian. I am also stoked to see what tetrapod fossils come out of this.

Monday, February 06, 2012

The Xenopermian is a collaborative effort between Scott, Raven, Zach and myself to outline a very different, speculative world. In some ways this is not all that different than the exercises of Dougal Dixon, After Man and The New Dinosaurs. Rather than speculating on what the dinosaurs would be like if they had not gone extinct, much like his New Dinosaurs or the Spec World project , or project into the future with After Man or The Future is Wild, our team asked the question of ‘what if the Permian Extinction did not happen?

This is the first post about the fauna of the Xenopermian in the Ural Sea region. We have talked about a ‘fossil’ and a faux controversy associated it with. We have talked about the geological staging differences in the XenoPermian timeline, and have even talked about the differences in the world in general under such a different period. We have generalized about the fauna, but now we want to get into specifics.

Despite the fact that the world is largely dominated by the different clades of therapsids, other major lineages are major participants in the ecology of the XenoPermian. Rather than start with a therapsid, we decided to talk about a parareptile first. That first critter is a pareiasaur. That begs the questions of what is a parareptile and what is a pareiasaur?

What are the parareptiles?

Parareptiles are a clade of amniotes that have been in the past often labeled ‘anapsids.’ Amniotes, vertebrate animals that have an amniotic sack and, for the most part, are terrestrial, were divided into different groups based on the shape and structure of their skulls. Synapsids are those that had a single hole in the skull for muscle to attach. Modern mammals are the only current survivors of that clade. Diapsids are the second group and currently comprise reptiles and birds except perhaps turtles. That will be explained later. Diapsids have two holes in their skulls for anchoring their jaw muscles. Finally, there was another large traditional group, the anapsids. These amniotes had no holes in their skulls. Traditionally, this included turtles as the sole surviving members of the clade, but with a vast number of extinct relatives. There was another group, the euryapsids, but they were a smaller group that was largely centered around the extinct marine reptiles.

It turns out that the shape and number of holes in the skull were not quite the best, most accurate way to group the different clades of animals. It is possible for diapsids to redevelop, for whatever reason, the anapsid (no hole) cranial condition. This was discovered when cladistics became the tool of choice by paleontologists to determine evolutionary relationships between fossils.

A number of families and genuses were shuffled around. Interestingly, the synapsids were untouched as a group. The diapsids largely held together, but the anapsids were slaughtered as far as a ‘natural group’ (meaning closely related and descended from a common ancestor). Some ‘anapsids’ were actually diapsids that had evolved or re-evolved the anapsid condition. When the arguing was done, the skull type that has been referred to as ‘anapsid’ applied to some species that were actually descended from the diapsids and many that were not. The proposal was made to rename the remaining anapsids that were not closely related to diapsids ‘parareptiles’ (next to reptiles) and accepted by the community as a whole.

The placement of turtles is fairly contentious. The pour critters are fought over whether they are members of a group that went through parallel evolution and evolved the anapsid condition from a diapsid ancestor or actually belonged back as a sole surviving members of the parareptiles. There is strong evidence that they are actually diapsids now from studying microRNA, but cladistic analysis by and large, well, almost consistently shows them to be parareptiles. This argument, as far as I can tell, has yet to be resolved.

Other than turtles, parareptiles comprise many fascinating and interesting groups. The seemingly first bipedal animals, the bolosaurs, are members of the group. The procolonphids are another interesting member. The nycoleters and their relatives are the first amniotes, it appears, to have evolved the middle ear from the apparently deaf ancestral condition. (Yes, the basal amniotes were deaf it seems, but that is another discussion for another time) Finally, most importantly for the Xenopermian and this post, the clade that we care about most is the pareiasaurs.

What were the pareiasaurs?

The pareiasaurs were one of the earliest large megafauna. They were herbivores that grew to be as large as ten feet long and were built like tanks. In fact, the pareiasaurs were the largest herbivores of their time and were built such that they housed a massive gut for digesting the tough plants of their era. Their teeth looked leaf like and not unlike those of iguanas

They were also tanks, as noted, and had scutes, osteoderms, in their skin. Most likely this was to deal with the very large and deadly gorgonopsids. Some have projected that the gorgons and pareiasarus were in an arms race where the armor of these critters built up to deal with the ever increasing size and viciousness of the canines of the gorgons.

In our time line, they went extinct during the Permian Extinction. However, our timeline iwe actually live in s not that of the Xenopermian. The Xenopermian didn’t have a PT Event to wipe out all life. True, the Siberian Traps did erupt, but more gradually and over the course of millions of years instead of violently in a relatively short burst. This caused a period of evolutionary innovation and turnover, but did not wipe out many of the large clades. The pareiasaurs benefitted from that time of innovation and went on to develop into interesting clades.

Elginiformes, Scutosauroformes and Therischia, oh my!

Xenopermian Pareiasauria cladogram

Technically, all of the surviving pareiasaurian of the Xenopermian are from Therischia. This is a particular clade within the pareiasaurian lineage. In paleontology, cladistics dictates that the different fossils found are evaluated as relatives rather than ancestors. Its highly unlikely, honestly, that any one fossil species found gave rise to others that are related since the fossil record is infamously and enormously incomplete. However, in our world that the Xenopermian, we know exactly who is descended from whom. Or rather what from what. In our timeline we have two different lineages of pareiasaurs that have survived through to the 15 million year mark before the Xenopermian-Jurassic Mass Extinction.

The first derives from the dwarf pareiasaur, Elginia, and is very common as solitary animals scattered about the more marginal habitats. There are several species and genuses in the Megavongo, for example. The Barred Quillosaur being an excellent example. They all have a generally sprawled stance and are heavy armored, but in a manor reminiscent of the thorny devils of modern day Australia. Though with some parallels to the styracaosaurian ceraptopsians (sans nasal and brow horns). However, while being very species and even somewhat genera diverse the elginiformes are not the most diverse nor “dominant” of the two pareiasaur lineages. That would be the scutosauriformes.

Scutosaurus was a rather large beast by modern standards. With being around ten feet long and a chest like a barrel, it weighed in over 1000 lbs. It had several innovations that made it – without the Permian Extinction – a potential founder of a new and important lineage. Some of these were the stance changes, massive expansion of the digestive tract, probable homeothermy and extensive increases in the armoring scutes. With the power of the massive selectivity of being the creators of this timeline, Scutosaurus went forth and begat several new clades. Three of those clades have survived into the late XenoPermian.

The most basal of them is Deimocephalia. These are large, sometimes up to 4.5m (15 ft) animals. They move in bull dominated herds over vast distances. They give some basic parental care to their young although this is pretty limited to guarding the nest and forming a protective barrier while en route between the young and the outside world. Their name, terror heads, derives from the fact that they have very fanciful, species specific, crown and frill ornamentation. This is more extreme in the males than females, but present in both. Additionally their skulls have thickened for further protection. They retain the ancestral scute armor of the scutosauriformes. This clade is most common in the plains and other open territories, but also present in smaller forms in the more open forests of the Xenopermian world that permit herding.

The next most derived clade is that of the Juggernautids. These are massive animals that in terms of mass, if not length, rival the sauropods of our time line. Between 6 meters (20 ft) and some species being as long as 10m (over 32 ft), they have developed the brachiosaurian layout with the forelegs being much longer than the hind. They tower over the landscape with heights between 4.5m (15ft) to as much as 6m (20ft) in the largest species. They do NOT have the extended long neck of the sauropods while one somewhat longer than the standard pareiasaurs in proportion. The juggernautids did not just get their name from their size, but also from the fact that they radically shape the environment from which they live. The bulldoze paths for food and often reduce forests to copses that are either inaccessible to the juggernautid, or ‘managed’ such that there is not an interior that the juggernautid cannot reach for feeding. Forests where juggernautids exist have a strange almost garden like appearance what seem like streets when viewed from above. Juggernautids are not noted for their parenting skills even if they mate for life. Their young are heavily armoured and their scutes tend to still be present but more scattered across the body as the animal grows, these primary scutes are surrounded by thinner, but still tough secondary scutes, which in turn are followed by tertiary scute development between those with straight scaly skin separating the rosarettes of the largest creatures.

Neither of the above clades is present around the Ural Sea. However, the final clade is.

The Pseudochelonids are a large, heavy herbivores. They are called the pseudochelonids (false turtles) because of their heavily armored carapaces. They have some elements that are convergent on turtles in that regard, with the scutes often fusing with the broad ribs in some genuses. Visually, most look closer to anklyosaurs rather than turtles, but the first example found of the clade was the most extreme in its armour development and set the nomenclature for the whole group.

Some of the unifying characteristics are that the ribs are broad and flat, almost forming a fused shell dorsally. This is often covered by scutes that are interlocking. The skulls are extremely thick and heavy: even their eyelids are armoured. The brain case is relatively small for an animal of their relative size as well. However, the olfactory and aural regions are relatively developed to support what is a very good sense of smell and moderately developed middle ear. They all have vestigal or nonexistent tails. Their scutes cover more than their torso region and extend down onto the legs. Like all scutosauriformes, they have a parasagittal stance.

They are by and large solitary animals, but do not have defined ranges except during mating season and tolerate one another quite well otherwise. They do not give parental care to their young, building a rocky nest and then abandoning them. The newly hatched young once their skin dries and hardens become what some atl paleontologists call ‘jaw breakers’ (fractognathine stage) because their scutes are so thick and dense. Their main sources of mortality once they have become jaw breakers are not predators, but rather disease and drowning. Post fractgnathinous stage starts when the animal reaches 1 meter (40 inches) in length because of the inability of the body to continue to scale up with such armor. When the animal has reached 1.5m (five feet) in length, it often is sexually mature, but while still heavily armoured, in danger from its primary predator: the gorgonopsids. In fact, the pseudochelonids and the gorgonopsids are in something of an arms race: heavier armour vs stronger bites and better piercing saber teeth.

Graviloricanasus roma

In the Ural Sea region the dominant member, both most common and largest, is Graviloricanasus roma (Roman’s heavily armored nose). Named for the discoverer, Thomas Roman, it became a bit of an in-joke because the olfactory organ – nose – was quite impressive and the great Roman Nose was too good to pass up. The belief is that the olfactory sense was highly developed for two reasons. The first was that it allowed G. roma to smell its primary predators and locate when particular foods were present.

Predation Around the Ural Sea

The gorgonopsids of the Ural Sea region were G roma's primary predators and were noted for scent marking their territories. A cross genera territorial struggle between the Baurbarops millerensis and Dispathadontis gracilis, the two large top predators in the Ural Sea left some very impressive olfactory battlefields. B. millerensis was rarer and larger gorgon largely preying on dicynodonts, especially, but definitely not exclusively, what has been popularly called the ‘Walrodonts.’ Other preferred dicynodonts included the other less specialized aquatic dicynodonts, such has the so called "Hippodonts," "desmodonts," and others. However, given the beach front territory of adult B milernensis and the sea weed dining habits of G roma, B millerensis will opportunistically predate this pseudochelonid. The sheer size and strength of B millernesis makes this predation possible despite the extensive armor of G roma.

Dispathadontis, while it could and would take other prey, was largely a specialist in pseudochelonids. In the Ural Sea region, this specifically means G roma. While B millerensis is noted for its brute force hunting style, D gracilis is more finessed. D gracilis is noted for hunting in mated pairs. The pairing will corner a G roma and then attempt to rip out its wind wipe through the use of their sabre teeth.

The only other predator of note of G roma is the ambush predator crurodont, Venofirodens macbethii, a member of the clade descended from the therocephalian Euchambersia. V macbethii relies, like all of its clade, on the delivery of a poisonous bite to its prey for it take-down mechanism rather than traumatic damage to an organism.

Of course, as eggs, G roma is at risk from a variety of potential predators. The cynodont genus, Acerdens, the small Xenopermian theropods, niictodonts, and even opportunistic raids from the trees by suminids and foliosensids can and do take their toll on the unhatched.

Diet Peculiarities

One of the benefits of the nasal system of G roma was that it also allowed for scenting food sources other than the norm for consumption. One of those is seaweed. The seaweeds that swept up from the very mixed waters of the Ural Sea are a nutritious addition to the normal diet. When the tide goes out, G roma often comes out of the coastal forest to dine, as pictured here. This is, however, the point that G roma is most in risk of predation from B millerensis.

However, for the majority of its nutritional needs, G roma browses within the Ural Sea coastal forests. Its diet is largely comprised of ferns and seed plant leaves. Its preference is not for horsetails or their allies, but will consume these during hard times.

Ecological Impact

G roma's impact on the local ecology is moderate, but appreciable. Its nothing like its remote cousins, the Juggernautids, but it is far from trivial. Within the Ural Sea coastal forests, wide avenues are present from the passage of G roma to and from certain locales, especially watering holes. This in turn, has stimulated seed baring plants to develop into upper canopy participants by leaving potential places for trees with wide boughs to collect light where the horsetails are unable to. Ginkgoes and others have taken advantage of this.

Other significant impacts are the specialization of Dispathadontis and the development of scatosporic ferns (dug heaps often sprout ferns in a massive way from consuming through an odd life cycle of certain fern species in the Ural Sea region).

Legacy

Graviloricanasus roma would last as a species for approximately three million years. Its genus would last to nearly the Xenopermian-Jurassic Extinction. All parieasaurs would go extinct during the XJ Event and take with them their "tormentors" and largely specialist carnivores, the gorgonopsids. It would be over 100 million years before another walking tank would arise, but it would not be another parareptile and it would happen outside the Xenopermian, well within the Mesozoic and embedded in the alternate Cretaceous. And thus, outside the scope of this project as yet.

Author's note:Here's our first critter. I hope that you folks enjoyed it. My apologies for the delay. Next up will be a therapsid. A notable little tree hugger for that matter. It will be a bit before it appears here, but hopefully not too long. I need yet another cladogram and its a far more complicated one than the above!

Wednesday, February 01, 2012

New research reveals how the arrival of the first plants 470 million years ago triggered a series of ice ages. Led by the Universities of Exeter and Oxford, the study is published today (1 February 2012) in Nature Geoscience.

The team set out to identify the effects that the first land plants had on the climate during the Ordovician Period, which ended 444 million years ago. During this period the climate gradually cooled, leading to a series of 'ice ages'. This global cooling was caused by a dramatic reduction in atmospheric carbon, which this research now suggests was triggered by the arrival of plants.

Among the first plants to grow on land were the ancestors of mosses that grow today. This study shows that they extracted minerals such as calcium, magnesium, phosphorus and iron from rocks in order to grow. In so doing, they caused chemical weathering of the Earth's surface. This had a dramatic impact on the global carbon cycle and subsequently on the climate. It could also have led to a mass extinction of marine life.

The research suggests that the first plants caused the weathering of calcium and magnesium ions from silicate rocks, such as granite, in a process that removed carbon dioxide from the atmosphere, forming new carbonate rocks in the ocean. This cooled global temperatures by around five degrees Celsius.

In addition, by weathering the nutrients phosphorus and iron from rocks, the first plants increased the quantities of both these nutrients going into the oceans, fuelling productivity there and causing organic carbon burial. This removed yet more carbon from the atmosphere, further cooling the climate by another two to three degrees Celsius. It could also have had a devastating impact on marine life, leading to a mass extinction that has puzzled scientists.

The team used the modern moss, Physcomitrella patens for their study. They placed a number of rocks, with or without moss growing on them, into incubators. Over three months they were able to measure the effects the moss had on the chemical weathering of the rocks.

They then used an Earth system model to establish what difference plants could have made to climate change during the Ordovician Period.

I've heard this put forward for the Devonian, but not the Ordovician. For that matter, the Azolla Event is another proposed biologically driven climate change. We'll see how this plays out. The timing is...tough...to prove, but we do know that life even nonsapient/sophont does impact climate.

A mysterious, centuries-long cool spell, dubbed the Little Ice Age, appears to have been caused by a series of volcanic eruptions and sustained by sea ice, a new study indicates.

The research, which looked at chemical clues preserved in Arctic vegetation as well as other data, also pinpointed the start of the Little Ice Age to the end of the 13th century.

During the cool spell, which lasted into the late 19th century, advancing glaciers destroyed northern European towns and froze the Thames River in London and canals in the Netherlands, places that are now ice-free. There is also evidence it affected other continents.

"This is the first time anyone has clearly identified the specific onset of the cold times marking the start of the Little Ice Age," said Gifford Miller, a geological sciences professor at the University of Colorado, Boulder, and the lead study researcher. "We also have provided an understandable climate feedback system that explains how this cold period could be sustained for a long period of time."

The cause appears to have been massive tropical volcanic eruptions, which spewed tiny particles called aerosols into the atmosphere. While suspended in the air, the aerosols reflect solar radiation back into space, cooling the planet below.

The cooling was sustained after the aerosols had left the atmosphere by a sea-ice feedback in the North Atlantic Ocean, the researchers believe. Expanding sea ice would have melted into the North Atlantic Ocean, interfering with the normal mixing between surface and deeper waters. This meant the water flowing back to the Arctic was colder, helping to sustain large areas of sea ice, which, in turn, reflect sunlight back into the atmosphere. The result was a self-sustaining feedback loop.

Miller and colleagues came to these conclusions by looking at radiocarbon dates — based on how much of the radioactive form of carbon they contain — from dead plants revealed by melting ice on Baffin Island, in the Canadian Arctic. Their analysis found that many plants at both high and low altitudes died between A.D. 1275 and A.D. 1300 — evidence that Baffin Island froze over suddenly. Many plants also appeared to have died at around A.D. 1450, an indication of a second major cooling.

These periods coincide with two of the most volcanically active half centuries in the past millennium, according to the researchers.

Let's see if they can provide more support. Its intriguing, but caution is in order.